JANUS LIPOSOMES: DESIGN, FORMATION AND ACTIVE MOTION

Abstract

The liposome is an amphiphilic molecule that contains both a hydrophilic head and a hydrophobic tail. As a class of biocompatible, water-dispersed colloids, liposomes have found widespread applications ranging from food to drug delivery. For example, liposomes can carry both hydrophilic and hydrophobic drugs because of their amphiphilic properties. This dissertation presents a series of studies on liposomes consisting of their preparation methods, self-assembly properties, and motion behaviors. In chapter 1, a brief introduction regarding liposomes is described, including some critical concepts, different preparation methods, and the main applications of liposomes. In chapter 2, a new type of liposomes, which contain opposite surface charges decorating the two hemispheres of the same colloidal body – dipolar Janus liposomes, is reported. We also follow the electrokinetic motion as well as electrostatic self-assembly of these new dipolar Janus particles. In Chapter 3, a general procedure for size-controlled preparation of giant unilamellar liposomes is demonstrated. The control of liposome size is realized through PC membranes. This procedure thus offers a simple and fast alternative route to size-controlled giant unilamellar liposomes. In Chapter 4, an approach successfully demonstrated of lipid assembly chemistry to a general audience is present. Consisted mainly of three straightforward hands-on experiments, this Activity enables most of the key concepts in lipid assembly chemistry to be conveyed to interested students. Lipid phase separation, an important area of current membrane biophysics research, is also covered. In Chapter 5, liposome active motion, taking advantage of mainly a pair of intrinsic material properties associated with these assemblies: lipid phase separation and extraction, is demonstrated. Our results highlight the rich possibility to hierarchically design lipid-based artificial motors, from individual lipids, to their organization, surface chemistry, and interfacial mechanics.